Current density simulation method, device, equipment and storage medium

Abstract

The present application is about a current density simulation method, device, equipment and storage medium, specifically related to the field of new energy. The method includes: obtaining the electrochemical parameters and physical parameters of the target battery; constructing an electrochemical thermal coupling model based on the electrochemical parameters and physical parameters; the electrochemical thermal coupling model is used to indicate the temperature and current state of the target battery in the working environment; inputting the target charging current into the electrochemical thermal coupling model, and detecting the current density distribution at each position in the target battery. Through the above scheme, the current density distribution state of the battery is simulated by simulation, so as to verify the safety of the target battery during the charging process.

Description

Technical Field

[0001] The present invention relates to the field of new energy, and in particular to a current density simulation method, device, equipment and storage medium. Background Art

[0002] The demand for new energy electric vehicles has increased dramatically, and lithium-ion power batteries, as the core components of electric vehicles, have an irreplaceable position.

[0003] The current lithium-ion battery charging technology is one of the keys to its application and is also a hot topic of research today. In order to reduce the charging time of power batteries, high current charging is often used. However, high current charging of power lithium-ion batteries will cause the battery temperature to rise suddenly, the capacity to decay, and the life to decrease. At present, the battery cell of the laminated battery is composed of layered positive and negative electrodes and separators stacked alternately. When the lithium-ion battery is in the charging working state, the electrons on the positive electrode run to the negative electrode through the external circuit, and the lithium ions enter the electrolyte from the inside of the positive electrode active material particles, migrate to the negative electrode, combine with the electrons already on the negative electrode, and enter the inside of the negative electrode active material particles. When the negative electrode has no position to accept lithium ions, lithium ions will precipitate on the surface of the negative electrode, forming lithium dendrites, piercing the diaphragm, causing an internal short circuit in the lithium-ion battery and causing thermal runaway.

[0004] In the above scheme, the characterization method cannot detect the current density distribution of the negative electrode of the lithium-ion battery, and can only roughly estimate the current density of the large surface through an approximate method (current divided by the area of ​​the large surface), which makes it difficult to verify the safety of the lithium-ion battery. Summary of the invention

[0005] The present application provides a current density simulation method, device, computer equipment and storage medium, which can verify the safety of the battery during the charging process. The technical solution is as follows.

[0006] In one aspect, a current density simulation method is provided, the method comprising:

[0007] Based on the battery parameters of the target battery, a discrete equivalent circuit model is constructed; the discrete equivalent circuit model includes various battery cell regions; the battery cell region includes battery cells and thermal capacitance elements; the battery cells are used to indicate the power generation status of the battery cell region; the thermal capacitance elements are used to indicate the temperature change of the battery cell region;

[0008] Based on the adjacency relationship between the various battery cell regions, according to the condition that the target battery cell operates under the specified working condition, a circuit simulation is performed on the target battery cell region to obtain the battery cell temperature corresponding to the target thermal capacitance element in the target battery cell region under the specified working condition.

[0009] In another aspect, a current density simulation device is provided, the device comprising:

[0010] A parameter acquisition module is used to obtain the electrochemical parameters and physical parameters of the target battery;

[0011] A model building module, used to build an electrochemical thermal coupling model according to the electrochemical parameters and physical parameters; the electrochemical thermal coupling model is used to indicate the temperature and current state of the target battery under the working environment;

[0012] The current density detection module is used to input the target charging current into the electrochemical thermal coupling model and detect the current density distribution at each position in the target battery.

[0013] In a possible implementation, the model building module is used to:

[0014] According to the electrochemical parameters, an electrochemical model is constructed; the electrochemical model is used to indicate the current distribution of each area of ​​the target battery under the target current state according to the target battery parameters;

[0015] Constructing a battery thermal model according to the physical parameters; the battery thermal model is used to indicate the temperature change of each area of ​​the target battery;

[0016] Based on the changing relationship between the target battery parameter and the temperature, and the corresponding relationship between the battery heating value and the current state, the electrochemical model and the battery thermal model are coupled to form the electrochemical thermal coupling model.

[0017] In a possible implementation, the physical parameter includes a size parameter of the target battery;

[0018] The device also includes:

[0019] A geometric construction module, used to construct a three-dimensional geometric model according to the size parameters of the target battery;

[0020] The model building module is also used to:

[0021] Constructing the electrochemical model according to the electrochemical parameters corresponding to each position in the three-dimensional geometric model;

[0022] The model building module is also used to:

[0023] The battery thermal model is constructed according to the thermodynamic parameters corresponding to each position in the three-dimensional geometric model.

[0024] In a possible implementation manner, the device further includes:

[0025] A prediction data acquisition module, used to perform discharge simulation processing on the electrochemical thermal coupling model to obtain predicted discharge data of the electrochemical thermal coupling model under different discharge states;

[0026] The model updating module is used to update the parameters of the electrochemical thermal coupling model based on the predicted discharge data under different discharge states and the actual discharge data of the target battery under different discharge states to obtain an updated electrochemical thermal coupling model.

[0027] In a possible implementation, the method further includes:

[0028] An update data acquisition module, used to perform discharge simulation processing on the updated electrochemical thermal coupling model to obtain updated discharge data of the updated electrochemical thermal coupling model under different discharge states;

[0029] a target model acquisition module, configured to determine the updated electrochemical thermal coupling model as a target electrochemical thermal coupling model when a difference between the predicted discharge data and the actual discharge data is less than a specified threshold;

[0030] The current density acquisition module is also used to:

[0031] The target charging current is input into the target electrochemical thermal coupling model, and the current density distribution at each position in the target battery is detected.

[0032] In a possible implementation manner, the device further includes:

[0033] A detection area acquisition module is used to obtain a target detection area;

[0034] A density distribution acquisition module, used for collecting the current density distribution in the target electrochemical thermal coupling model in the target detection area;

[0035] The battery status determination module is used to determine the target battery as being in a dangerous state when the current density distribution corresponding to the target detection area is greater than the current threshold corresponding to the target detection area.

[0036] On the other hand, a computer device is provided, comprising a processor and a memory, wherein the memory stores at least one instruction, and the at least one instruction is loaded and executed by the processor to implement the above-mentioned current density simulation method.

[0037] On the other hand, a computer-readable storage medium is provided, wherein at least one instruction is stored in the storage medium, and the at least one instruction is loaded and executed by a processor to implement the above-mentioned current density simulation method.

[0038] In another aspect, a computer program product or a computer program is provided, wherein the computer program product or the computer program comprises computer instructions, wherein the computer instructions are stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the above-mentioned current density simulation method.

[0039] The technical solution provided by this application may have the following beneficial effects:

[0040] Since it is difficult to detect the current density distribution of each lithium battery on the electrode surface in a lithium battery, an electrochemical-thermal coupling model can be constructed based on the electrochemical parameters and physical parameters during battery design to simulate the temperature and current state of the target battery in the working environment. At this time, a high-power charging current can be set in the electrochemical-thermal coupling model to calculate the current density distribution of each position in the electrochemical-thermal coupling model under the condition of high-power charging current, so as to simulate the current density distribution state of the battery through simulation, thereby verifying the safety of the target battery during the charging process. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the specific implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0042] Figure 1 It is a schematic structural diagram of a current density simulation system according to an exemplary embodiment.

[0043] Figure 2 is a method flow chart of a current density simulation method according to an exemplary embodiment.

[0044] Figure 3 is a method flow chart of a current density simulation method according to an exemplary embodiment.

[0045] Figure 4 A schematic diagram of a three-dimensional geometric model involved in an embodiment of the present application is shown.

[0046] Figure 5 A schematic diagram of an Overhang structure involved in an embodiment of the present application is shown.

[0047] Figure 6It is a flow chart of a simulation method for predicting the current density at the overhang of the negative electrode of a lithium-ion battery according to an exemplary embodiment of the present application.

[0048] Figure 7 A schematic diagram of comparison of electrochemical-thermal coupling model correction data involved in an embodiment of the present application is shown.

[0049] Figure 8 A schematic diagram of current density distribution simulated by an embodiment of the present application is shown.

[0050] Fig. 9 It is a structural block diagram of a current density simulation device according to an exemplary embodiment.

[0051] Fig.10 A structural block diagram of a computer device shown in an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0052] The technical solution of the present application will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0053] It should be understood that the "indication" mentioned in the embodiments of the present application can be a direct indication, an indirect indication, or an indication of an association relationship. For example, A indicates B, which can mean that A directly indicates B, for example, B can be obtained through A; it can also mean that A indirectly indicates B, for example, A indicates C, and B can be obtained through C; it can also mean that there is an association relationship between A and B.

[0054] In the description of the embodiments of the present application, the term "corresponding" may indicate a direct or indirect correspondence between two items, or an association relationship between the two items, or a relationship between indication and being indicated, configuration and being configured, and the like.

[0055] In an embodiment of the present application, "predefinition" can be achieved by pre-saving corresponding codes, tables or other methods that can be used to indicate relevant information in a device (for example, including a terminal device and a network device). The present application does not limit its specific implementation method.

[0056] Figure 1 1 is a schematic diagram of a current density simulation system according to an exemplary embodiment. The current density simulation method system includes a server 110 and a terminal 120 .

[0057] The terminal 120 may be a data processing device with data processing capabilities. When the terminal 120 receives the battery parameters (electrochemical parameters and physical parameters) of the target battery input by the user, an electrochemical-thermal coupling model may be constructed according to the battery parameters.

[0058] For example, the terminal 120 runs three-dimensional physical simulation software, which may be COMSOL. The user may input the electrochemical parameters and thermodynamic parameters (such as specific heat capacity) of the battery cells corresponding to each region of the pre-set target battery into COMSOL to construct an electrochemical model and a battery thermal model of the target battery.

[0059] Optionally, the three-dimensional physical simulation software can run in the server 110. When the user inputs the preset parameters of the target battery from the terminal 120, the terminal 120 can transmit the parameters to the server 110 through the communication network, so that the server 110 constructs an electrochemical thermal coupling model according to the battery parameters and performs corresponding current density simulation.

[0060] Optionally, the battery parameters of the target battery may also be pre-stored in the server 110 or the terminal 120 .

[0061] Optionally, the above-mentioned server can be an independent physical server, or a server cluster or distributed system composed of multiple physical servers. It can also be a cloud server that provides cloud services, cloud databases, cloud computing, cloud functions, cloud storage, network services, cloud communications, middleware services, domain name services, security services, CDN, as well as big data and artificial intelligence platforms and other technical computing services.

[0062] Optionally, the system may further include a management device, which is used to manage the system (such as managing the connection status between each module and the server, etc.), and the management device is connected to the server via a communication network. Optionally, the communication network is a wired network or a wireless network.

[0063] Optionally, the above-mentioned wireless network or wired network uses standard communication technology and / or protocol. The network is usually the Internet, but it can also be any other network, including but not limited to any combination of local area network, metropolitan area network, wide area network, mobile, limited or wireless network, private network or virtual private network. In some embodiments, the technology and / or format including hypertext markup language, extensible markup language, etc. are used to represent the data exchanged through the network. In addition, conventional encryption technologies such as secure socket layer, transport layer security, virtual private network, Internet protocol security, etc. can also be used to encrypt all or some links. In other embodiments, customized and / or dedicated data communication technology can also be used to replace or supplement the above-mentioned data communication technology.

[0064] Figure 2 is a method flow chart of a current density simulation method according to an exemplary embodiment. The method is executed by a computer device, which may be as follows Figure 1 The server 110 in the current density simulation system shown in FIG. Figure 1 Terminal 120 in the current density simulation system shown in FIG. Figure 2 As shown, the current density simulation method may include the following steps:

[0065] Step 201, obtaining electrochemical parameters and physical parameters of a target battery.

[0066] The electrochemical parameters are used to characterize the chemical properties of the target battery, such as the maximum lithium ion concentration of the target battery, the lithium ion concentration of the electrolyte, the electrochemical reaction rate, etc. The physical parameters are used to characterize the physical properties or geometric structure of the target battery, for example, the physical parameters may include geometric parameters such as the length, width, height, thickness, etc. of the target battery, and may also include the specific heat capacity of the electrolyte of the target battery, etc.

[0067] Step 202: construct an electrochemical-thermal coupling model according to the electrochemical parameters and the physical parameters.

[0068] The electrochemical thermal coupling model is used to indicate the temperature condition and current state of the target battery under the working environment.

[0069] After the computer device obtains the electrochemical parameters and physical parameters, an electrochemical thermal coupling model can be constructed based on the electrochemical parameters and physical parameters. For example, the electrochemical thermal coupling model can be executed through three-dimensional physical simulation COMSOL. That is, the computer device can input the obtained electrochemical parameters and physical parameters into the three-dimensional physical simulation software. After the simulation software receives the electrochemical parameters and physical parameters, it will couple the electrochemical model with the battery thermal model according to the dependency relationship between the various parameters, thereby obtaining the electrochemical thermal coupling model.

[0070] For example, in the electrochemical model, the reaction rate of the target battery (i.e., the flow rate of ions) is related to temperature, and the reaction of the target battery will also cause heat and thus affect the temperature. Therefore, there is a mutual influence between the electrochemical model and the battery thermal model. By inputting electrochemical parameters and pre-configured equations, the three-dimensional physical simulation COMSOL can generate the electrochemical thermal coupling model.

[0071] Step 203 , input the target charging current into the electrochemical thermal coupling model, and detect the current density distribution at each position in the target battery.

[0072] After the electrochemical-thermal coupling model is constructed, the change in parameters in the electrochemical-thermal coupling model when the target charging current of the specified current magnitude is input can be simulated in the three-dimensional simulation software, thereby equivalently simulating the actual changes in various parameters inside the target battery when the target battery is charged with the target charging current of the specified current magnitude.

[0073] Therefore, in the three-dimensional simulation software, the current density at each position can be directly read, that is, the simulation of the current density distribution at each position in the target battery can be obtained.

[0074] To summarize, since it is difficult to detect the current density distribution of each lithium battery on the electrode surface in a lithium battery, an electrochemical-thermal coupling model can be constructed based on the electrochemical parameters and physical parameters during battery design to simulate the temperature and current state of the target battery in the working environment; at this time, a high-power charging current can be set in the electrochemical-thermal coupling model, and the current density distribution of each position in the electrochemical-thermal coupling model under the condition of high-power charging current can be calculated, so as to simulate the current density distribution state of the battery through simulation, thereby verifying the safety of the target battery during the charging process.

[0075] Figure 3 is a method flow chart of a current density simulation method according to an exemplary embodiment. The method is executed by a computer device, which may be as follows Figure 1 The server 110 in the current density simulation system shown in FIG. Figure 1 Terminal 120 in the current density simulation system shown in FIG. Figure 3 As shown, the current density simulation method may include the following steps:

[0076] Step 301, obtaining electrochemical parameters and physical parameters of a target battery.

[0077] Since the target battery is an actually designed battery, the electrochemical parameters and physical parameters of the battery are known, that is, the electrochemical parameters and physical parameters of the target battery can be input into the computer device by the user, or obtained by the computer device from a pre-existing battery parameter database.

[0078] Whether it is physical parameters or electrochemical parameters, the actual geometric characteristics of the target battery must be taken into account. For example, in the target battery, only the positive and negative electrodes have the concept of conductivity, and the diaphragm is not conductive. Therefore, the physical parameters and electrochemical parameters obtained are actually parameter information corresponding to a certain area.

[0079] For example, the electrochemical parameters of the target battery may be as shown in Table 1.

[0080]

[0081]

[0082] Table 1 shows the battery parameters of the electrochemical thermal coupling model. For example, the physical parameters of the target battery can be shown in Table 2.

[0083]

[0084] Table 2 shows the battery parameters of the electrochemical thermal coupling model

[0085] As shown in Table 1 and Table 2, different parts have different types of electrochemical parameters or physical parameters, and different parts usually have different values ​​of electrochemical parameters and physical parameters.

[0086] Step 302: construct an electrochemical model according to the electrochemical parameters.

[0087] The electrochemical model is used to indicate the current distribution of various regions of the target battery under a target current state according to the target battery parameters.

[0088] For example, for the electrochemical reaction mechanism of lithium-ion batteries, relevant kinetic equations are used to describe the internal electrochemical process. The specific process is as follows;

[0089] The diffusion of lithium ions from the inside of positive and negative electrode particles to the surface of particles uses Fick's diffusion law to describe the conservation of solid-phase lithium ion substances, and the equation is as follows:

[0090]

[0091] Electrochemical reactions occur at the interface between the positive and negative electrode particles and the electrolyte (side reactions generally also occur at this interface), using the Butler-Volmer equation, which is expressed as follows:

[0092]

[0093] η=φ s -φ l -E eq -JR film

[0094] Lithium ions move from the inside of the particle to the outer boundary of the particle, and then enter the electrolyte through the interface reaction. During this process, the potential changes, which is described by the solid phase charge conservation equation, and its expression is as follows:

[0095]

[0096] The pores of the positive and negative porous electrodes and the diaphragm are filled with electrolyte, and lithium ions undergo mass transfer in the electrolyte using the Nernst-Plank equation, which is expressed as follows.

[0097]

[0098] Lithium ions migrate from the solid phase to the liquid phase, and during the movement in the liquid phase, potential changes will also occur. Using the liquid phase charge conservation equation, the expression is as follows.

[0099]

[0100] The porosity and tortuosity of the positive and negative porous electrodes and the diaphragm are different, and the movement trajectories of lithium ions are also different. The conductivity and diffusion coefficient of the electrolyte in the positive and negative porous electrodes and the diaphragm area must be corrected, and the correction equation is as follows.

[0101]

[0102] Here, the physical parameters involved in the present invention are explained and adapted to the above formulas. Cs is the average concentration of lithium ions in the solid phase (mol / m^3), Ds is the solid phase diffusion coefficient (m^2*s), r is the solid phase particle radius, t is the diffusion time, J is the local reaction current density (A / m^2), a v is the specific surface area (1 / m), i 0 is the exchange current density (A / m^2), a a , a c is the positive and negative transfer coefficients, F is the Faraday constant (96487C / mol), η is the overpotential (V), R is the universal gas constant (8.314J / (mol*K)), T is the temperature (K), k a , k c is the electrochemical reaction rate coefficient of cation and anion (m / s), Cs,max is the maximum lithium ion concentration in the solid phase (mol / m^3), Cs is the solid phase lithium ion concentration (mol / m^3), C l , C l,ref is the electrolyte salt concentration, reference concentration (mol / m^3), φ s is the solid phase potential (V), φ l is the liquid potential (V), Eeq is the circuit voltage (V), R film is the membrane resistance (Ω), φ s is the solid phase potential (V), σ s eff is the effective diffusion coefficient of solid-phase lithium ions, D l eff is the effective diffusion coefficient of lithium ions in liquid phase, t + 0is the lithium ion migration number, T is the lithium ion battery temperature (K), h is the convection heat transfer coefficient (W / (K*m^2)), Tamb is the temperature at room temperature (K), q is the heat generation rate (W / m^3), ρ is the density (Kg / m^3), Cp is the heat capacity (J / (Kg*K)), d i is the thickness of each layer of material, k r , k z Represent the radial and axial thermal conductivities of the battery cell respectively.

[0103] Through the above equation, the movement of lithium ions in the electrochemical reaction under specified parameters and specified reaction conditions can be determined.

[0104] Step 303: construct a battery thermal model according to the physical parameters.

[0105] The battery thermal model is used to indicate the temperature changes in various areas of the target battery. During the operation of lithium-ion batteries, the electrochemical reaction model cannot fully and accurately reflect the actual operating state of lithium ions.

[0106] In the electrochemical reaction process of lithium-ion batteries, heat is generally generated by the movement of lithium ions, the movement of electrons and related electrochemical reactions, and the generated heat is transferred in various components. Since the thermal conductivity of each component is different, the heat exchange with the outside world will lead to the temperature distribution of the lithium-ion battery, and different temperature distributions will cause the electrochemical reaction rate of different parts of the lithium-ion battery to change, thereby affecting the current density. Heat conduction in lithium ions satisfies the law of conservation of energy:

[0107]

[0108] Calculate the thermal conductivity in different directions, including the thermal conductivity in the thickness direction: Axial thermal conductivity: k r ∑ i d i =∑ i k i d i .

[0109] In one possible implementation, the physical parameters include the size parameters of the target battery; the three-dimensional geometric model is constructed based on the size parameters of the target battery; the electrochemical model is constructed based on the electrochemical parameters corresponding to each position in the three-dimensional geometric model; and the battery thermal model is constructed based on the thermodynamic parameters corresponding to each position in the three-dimensional geometric model.

[0110] Before constructing the electrochemical model and the battery thermal model (ie, the thermodynamic model), a three-dimensional geometric model corresponding to the target battery may be constructed based on the size parameters of the target battery to indicate the size characteristics of the target battery.

[0111] Optionally, the three-dimensional geometric model may be modeled by CAD software; or the three-dimensional geometric model may be modeled by three-dimensional physical simulation software integrated with CAD function.

[0112] After obtaining the three-dimensional geometric model, the battery parameters corresponding to each area of ​​the target battery can be matched with each area in the three-dimensional geometric model through the three-dimensional physical simulation software, so as to construct a complete electrochemical model and battery thermal model. According to the above electrochemical equations and thermal reaction equations, the extracted relevant parameters are input into the model settings in the three-dimensional physical simulation software, and the geometric model is adaptively meshed, so as to complete the electrochemical-thermal coupling modeling of the simulated model.

[0113] Please refer to Figure 4 , which shows a schematic diagram of a three-dimensional geometric model involved in an embodiment of the present application. Figure 4 As shown in the figure, the three-dimensional geometric optimization model consists of seven parts (with the thickness direction of the battery cell as the axis), in the following order: negative electrode tab, negative electrode current collector, negative electrode porous electrode, separator, positive electrode porous electrode, positive electrode current collector, and positive electrode tab. Figure 2 Add material properties to the corresponding geometric model area, including positive and negative electrodes, electrolyte, current collector, separator, positive and negative electrode ears. The excess area of ​​the negative electrode relative to the positive electrode size is Overhang.

[0114] Overhang refers to the excess of the negative electrode sheet in length and width beyond the positive and negative electrode sheets. Overhang is designed to ensure that during stacking of the positive and negative electrode sheets, there is always a negative electrode opposite the positive electrode, even if the positive and negative electrode foils are slightly misaligned.

[0115] Step 304 , based on the changing relationship between the target battery parameter and the temperature, and the corresponding relationship between the battery heat generation and the current state, the electrochemical model and the battery thermal model are coupled into the electrochemical thermal coupling model.

[0116] When the relationship between the target battery parameters and the temperature is obtained, it is possible to determine how the target battery parameters are affected by the temperature change; and the temperature change of the target battery is related to the working heat of the target battery; and the working heat of the target battery is related to the rate of the electrochemical reaction. Therefore, according to the relationship between the target battery parameters and the temperature, and the corresponding relationship between the battery heat generation and the current state, the electrochemical model and the battery thermal model can actually be established as a coupling relationship. Through the various equations in step 302, the simulation software can achieve the coupling of the electrochemical model and the battery thermal model, thereby calculating the electrochemical properties (such as current density) and physical thermal properties (such as temperature) of the target battery under specified working conditions.

[0117] In one possible implementation, a discharge simulation process is performed on the electrochemical thermal coupling model to obtain predicted discharge data of the electrochemical thermal coupling model under different discharge states; based on the predicted discharge data under different discharge states and the actual discharge data of the target battery under different discharge states, the parameters of the electrochemical thermal coupling model are updated to obtain an updated electrochemical thermal coupling model.

[0118] In order to ensure the accuracy of the electrochemical thermal coupling model, after the electrochemical thermal coupling model is constructed, the electrochemical thermal coupling model can be subjected to discharge simulation in the simulation software. For example, a certain discharge rate is set for the target battery simulated by the electrochemical thermal coupling model. At this time, the simulation software can calculate the predicted discharge data of the electrochemical thermal coupling model during the discharge process (such as the change of voltage over time).

[0119] After obtaining the predicted discharge data simulated by the simulation software, it can be compared with the actual discharge data of the target battery at a specified discharge rate, the difference can be calculated, and the parameters in the electrochemical thermal coupling model can be updated to obtain an updated electrochemical thermal coupling model.

[0120] Optionally, in the process of updating the parameters of the electrochemical-thermal coupling model, the parameters to be updated may be predetermined, such as the correction coefficients in Table 1, so as to adaptively update the electrochemical-thermal coupling model according to the difference.

[0121] In one possible implementation, discharge simulation processing is performed on the updated electrochemical thermal coupling model to obtain updated discharge data of the updated electrochemical thermal coupling model under different discharge states; when the difference between the predicted discharge data and the actual discharge data is less than a specified threshold, the updated electrochemical thermal coupling model is determined as the target electrochemical thermal coupling model; the target charging current is input into the target electrochemical thermal coupling model, and the current density distribution at each position in the target battery is detected.

[0122] After the electrochemical thermal coupling model has been updated according to the difference value through the discharge simulation processing, the discharge simulation processing can be performed again, and the difference value can be calculated again. When the difference between the predicted discharge data and the actual discharge data is less than the specified threshold, the updated electrochemical thermal coupling model is determined as the target electrochemical thermal coupling model; at this time, the target electrochemical thermal coupling model is very similar to the actual electrochemical properties of the target battery, so the target charging current can be simulated by the target electrochemical thermal coupling model to detect the current density distribution at various positions of the target battery indicated by the target electrochemical thermal coupling model.

[0123] In one possible implementation, a charging simulation process is performed on the electrochemical thermal coupling model to obtain predicted charging data of the electrochemical thermal coupling model under different charging currents; based on the predicted charging data under different discharge states and the actual charging data of the target battery under different discharge states, the parameters of the electrochemical thermal coupling model are updated to obtain an updated electrochemical thermal coupling model.

[0124] After obtaining the predicted charging data simulated by the simulation software, it can be compared with the actual charging data of the target battery at a specified charging rate, the difference can be calculated, and the parameters in the electrochemical thermal coupling model can be updated to obtain an updated electrochemical thermal coupling model.

[0125] Step 305 , input the target charging current into the electrochemical thermal coupling model, and detect the current density distribution at each position in the target battery.

[0126] When the electrochemical thermal coupling model is constructed and the electrochemical thermal coupling model is very similar to the electrochemical properties of the target battery, the target charging current can be directly input into the electrochemical thermal coupling model to detect the current density distribution at various locations in the target battery.

[0127] In one possible implementation, a target detection area is acquired; on the target detection area, a current density distribution in the target electrochemical thermal coupling model is collected; when the current density distribution corresponding to the target detection area is greater than a current threshold corresponding to the target detection area, the target battery is determined to be in a dangerous state.

[0128] In the simulation software, a certain area or several areas in the electrochemical thermal coupling model can be pre-set as the target detection area. In this case, the simulation software can automatically collect the current density distribution in the target electrochemical thermal coupling model after simulation; and when the current density distribution to be detected is greater than the current threshold corresponding to the target detection area, it means that the target battery may have lithium precipitation, which may cause danger.

[0129] In a possible implementation, the target detection area is an overhang area in the target battery.

[0130] Please refer to Figure 5 , which shows a schematic diagram of an Overhang structure involved in an embodiment of the present application. Figure 5 As shown, the outer area is the Overhang area. The design of Overhang is to ensure that during the stacking of the positive and negative electrode sheets, even if the positive and negative electrode foils are slightly misaligned, there is always a negative electrode opposite to the positive electrode. However, during the charging process, some lithium ions will diffuse into the excess area of ​​the negative electrode, that is, the Overhang area, and this diffusion process will cause a certain capacity loss. At the same time, there will be a large current density at the edge of the positive electrode sheet facing the negative electrode, which will pose a certain risk of lithium precipitation and local overheating. In the operation of lithium-ion batteries, if there is an uneven distribution of current density or a local excessive phenomenon, the active materials of the lithium-ion battery cannot be fully utilized, and the discharge platform becomes lower during high current discharge, affecting the battery rate performance and local lithium precipitation. Therefore, in the embodiment of the present application, whether the current density on the Overhang can be accurately judged is also crucial to ensuring the safety of the target battery.

[0131] To summarize, since it is difficult to detect the current density distribution of each lithium battery on the electrode surface in a lithium battery, an electrochemical-thermal coupling model can be constructed based on the electrochemical parameters and physical parameters during battery design to simulate the temperature and current state of the target battery in the working environment; at this time, a high-power charging current can be set in the electrochemical-thermal coupling model, and the current density distribution of each position in the electrochemical-thermal coupling model under the condition of high-power charging current can be calculated, so as to simulate the current density distribution state of the battery through simulation, thereby verifying the safety of the target battery during the charging process.

[0132] Please refer to Figure 6 , which is a flow chart of a simulation method for predicting the current density at the overhang of the negative electrode of a lithium-ion battery according to an exemplary embodiment of the present application. Figure 6 As shown, the method can be shown in the following steps.

[0133] Step 601, parameter acquisition.

[0134] In the embodiment of the present application, a lithium iron phosphate + graphite, 4Ah capacity laminated lithium ion battery is used, lithium iron phosphate is used as the positive electrode, and graphite is used as the negative electrode. The basic physical properties and electrochemical parameters of this type of battery are obtained through experimental testing, literature search and other methods, and the parameters can be shown in Table 1.

[0135] Step 602, construct a model.

[0136] Establish a three-dimensional electrochemical model and a three-dimensional thermal model. Input relevant parameters into the electrochemical-thermal coupling model to complete the preliminary modeling of the electrochemical-thermal coupling model.

[0137] Step 603, actual discharge processing.

[0138] At room temperature of 25°C, the prepared lithium-ion batteries were discharged at different rates (0.33C, 0.5C, 1C), and the voltage and other data of the lithium-ion batteries changing with time were recorded.

[0139] Step 604: Model optimization processing.

[0140] Please refer to Figure 7 , which shows a schematic diagram of comparison of electrochemical-thermal coupling model correction data involved in the embodiment of the present application. Figure 7 The difference between the measured data and the simulated data of the lithium-ion battery shown is used to optimize the parameters in the electrochemical-thermal coupling model, and the parameters are returned to the model to obtain the optimized electrochemical-thermal coupling model, thus completing the final electrochemical-thermal coupling model setting.

[0141] Step 605, current density distribution calculation.

[0142] like Figure 8 As shown, it shows a schematic diagram of a current density distribution simulated by an embodiment of the present application. Set at 25°C, use an electrochemical-thermal coupling model, with an initial state of 0% SOC, give a certain current (step charging (charged to 50% SOC at 2.5C, then charged to 80% SOC at 1.7C, and then charged to 4.2V at 0.5C)), input to the corresponding model current interface, through model calculation, post-processing can obtain the current density at the overhang of the negative electrode of the lithium-ion battery, and the current density distribution at various positions inside the battery cell.

[0143] Fig. 9 1 is a block diagram of a current density simulation device according to an exemplary embodiment. The current density simulation device includes:

[0144] Parameter acquisition module 901, used to acquire electrochemical parameters and physical parameters of the target battery;

[0145] A model building module 902 is used to build an electrochemical thermal coupling model according to the electrochemical parameters and the physical parameters; the electrochemical thermal coupling model is used to indicate the temperature and current state of the target battery under the working environment;

[0146] The current density detection module 903 is used to input the target charging current into the electrochemical thermal coupling model and detect the current density distribution at each position in the target battery.

[0147] In a possible implementation, the model building module is used to:

[0148] According to the electrochemical parameters, an electrochemical model is constructed; the electrochemical model is used to indicate the current distribution of each area of ​​the target battery under the target current state according to the target battery parameters;

[0149] Constructing a battery thermal model according to the physical parameters; the battery thermal model is used to indicate the temperature change of each area of ​​the target battery;

[0150] Based on the changing relationship between the target battery parameter and the temperature, and the corresponding relationship between the battery heating value and the current state, the electrochemical model and the battery thermal model are coupled to form the electrochemical thermal coupling model.

[0151] In a possible implementation, the physical parameter includes a size parameter of the target battery;

[0152] The device also includes:

[0153] A geometric construction module, used to construct a three-dimensional geometric model according to the size parameters of the target battery;

[0154] The model building module is also used to:

[0155] Constructing the electrochemical model according to the electrochemical parameters corresponding to each position in the three-dimensional geometric model;

[0156] The model building module is also used to:

[0157] The battery thermal model is constructed according to the thermodynamic parameters corresponding to each position in the three-dimensional geometric model.

[0158] In a possible implementation manner, the device further includes:

[0159] A prediction data acquisition module, used to perform discharge simulation processing on the electrochemical thermal coupling model to obtain predicted discharge data of the electrochemical thermal coupling model under different discharge states;

[0160] The model updating module is used to update the parameters of the electrochemical thermal coupling model based on the predicted discharge data under different discharge states and the actual discharge data of the target battery under different discharge states to obtain an updated electrochemical thermal coupling model.

[0161] In a possible implementation, the method further includes:

[0162] An update data acquisition module, used to perform discharge simulation processing on the updated electrochemical thermal coupling model to obtain updated discharge data of the updated electrochemical thermal coupling model under different discharge states;

[0163] a target model acquisition module, configured to determine the updated electrochemical thermal coupling model as a target electrochemical thermal coupling model when a difference between the predicted discharge data and the actual discharge data is less than a specified threshold;

[0164] The current density acquisition module is also used to:

[0165] The target charging current is input into the target electrochemical thermal coupling model, and the current density distribution at each position in the target battery is detected.

[0166] In a possible implementation manner, the device further includes:

[0167] A detection area acquisition module is used to obtain a target detection area;

[0168] A density distribution acquisition module, used for collecting the current density distribution in the target electrochemical thermal coupling model in the target detection area;

[0169] The battery status determination module is used to determine the target battery as being in a dangerous state when the current density distribution corresponding to the target detection area is greater than the current threshold corresponding to the target detection area.

[0170] To summarize, since it is difficult to detect the current density distribution of each lithium battery on the electrode surface in a lithium battery, an electrochemical-thermal coupling model can be constructed based on the electrochemical parameters and physical parameters during battery design to simulate the temperature and current state of the target battery in the working environment; at this time, a high-power charging current can be set in the electrochemical-thermal coupling model, and the current density distribution of each position in the electrochemical-thermal coupling model under the condition of high-power charging current can be calculated, so as to simulate the current density distribution state of the battery through simulation, thereby verifying the safety of the target battery during the charging process.

[0171] Fig.10The structural block diagram of a computer device 1000 shown in an exemplary embodiment of the present application is shown. The computer device can be implemented as a server in the above-mentioned solution of the present application. The computer device 1000 includes a central processing unit (CPU) 1011, a system memory 1004 including a random access memory (RAM) 1002 and a read-only memory (ROM) 1003, and a system bus 1005 connecting the system memory 1004 and the central processing unit 1011. The computer device 1000 also includes a large-capacity storage device 1006 for storing an operating system 1009, an application program 1100 and other program modules 1011.

[0172] The mass storage device 1006 is connected to the central processing unit 1011 via a mass storage controller (not shown) connected to the system bus 1005. The mass storage device 1006 and its associated computer readable medium provide non-volatile storage for the computer device 1000. That is, the mass storage device 1006 may include a computer readable medium (not shown) such as a hard disk or a compact disc read-only memory (CD-ROM) drive.

[0173] Without loss of generality, the computer-readable medium may include computer storage media and communication media. Computer storage media include volatile and non-volatile, removable and non-removable media implemented by any method or technology for storing information such as computer-readable instructions, data structures, program modules or other data. Computer storage media include RAM, ROM, Erasable Programmable Read Only Memory (EPROM), Electronically-Erasable Programmable Read-Only Memory (EEPROM) flash memory or other solid-state storage technology, CD-ROM, Digital Versatile Disc (DVD) or other optical storage, cassettes, tapes, disk storage or other magnetic storage devices. Of course, those skilled in the art will appreciate that the computer storage medium is not limited to the above. The above-mentioned system memory 1004 and mass storage device 1006 can be collectively referred to as memory.

[0174] According to various embodiments of the present disclosure, the computer device 1000 can also be connected to a remote computer on a network through a network such as the Internet. That is, the computer device 1000 can be connected to the network 1008 through the network interface unit 1007 connected to the system bus 1005, or the network interface unit 1007 can be used to connect to other types of networks or remote computer systems (not shown).

[0175] The memory further includes at least one computer program, which is stored in the memory. The central processor 1011 implements all or part of the steps in the methods shown in the above embodiments by executing the at least one computer program.

[0176] In an exemplary embodiment, a computer-readable storage medium is also provided, which is used to store at least one computer program, and the at least one computer program is loaded and executed by a processor to implement all or part of the steps in the above method. For example, the computer-readable storage medium can be a read-only memory (ROM), a random access memory (RAM), a compact disc read-only memory (CD-ROM), a magnetic tape, a floppy disk, an optical data storage device, etc.

[0177] In an exemplary embodiment, a computer program product or a computer program is also provided, the computer program product or the computer program comprising computer instructions, the computer instructions being stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium, and the processor executes the computer instructions, so that the computer device performs the above-mentioned Figure 2 or Figure 3 All or part of the steps of the method shown in any embodiment.

[0178] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the following claims.

[0179] It should be understood that the present application is not limited to the precise structures that have been described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A current density simulation method, characterized in that: The method comprises: Obtain the electrochemical parameters and physical parameters of the target battery; Constructing an electrochemical thermal coupling model according to the electrochemical parameters and the physical parameters; the electrochemical thermal coupling model is used to indicate the temperature and current state of the target battery under the working environment; Performing discharge simulation processing on the electrochemical thermal coupling model to obtain predicted discharge data of the electrochemical thermal coupling model under different discharge states; Based on the predicted discharge data under different discharge states and the actual discharge data of the target battery under different discharge states, the parameters of the electrochemical thermal coupling model are updated to obtain an updated electrochemical thermal coupling model; Performing discharge simulation processing on the updated electrochemical thermal coupling model to obtain updated discharge data of the updated electrochemical thermal coupling model under different discharge states; When the difference between the predicted discharge data and the actual discharge data is less than a specified threshold, determining the updated electrochemical thermal coupling model as a target electrochemical thermal coupling model; Inputting a target charging current into the target electrochemical thermal coupling model, and detecting a current density distribution at each position in the target battery; The electrochemical-thermal coupling model is constructed according to the electrochemical parameters and the physical parameters, comprising: According to the electrochemical parameters, an electrochemical model is constructed; the electrochemical model is used to indicate the current distribution of each area of ​​the target battery under the target current state according to the target battery parameters; Constructing a battery thermal model according to the physical parameters; the battery thermal model is used to indicate the temperature change of each area of ​​the target battery; Based on the changing relationship between the target battery parameter and the temperature, and the corresponding relationship between the battery heat generation and the current state, the electrochemical model and the battery thermal model are coupled to form the electrochemical thermal coupling model.

2. The method according to claim 1, characterized in that The physical parameters include size parameters of the target battery; Before constructing the electrochemical thermal coupling model according to the electrochemical parameters and the physical parameters, the method further includes: Constructing a three-dimensional geometric model according to the size parameters of the target battery; The step of constructing an electrochemical model according to the electrochemical parameters comprises: Constructing the electrochemical model according to the electrochemical parameters corresponding to each position in the three-dimensional geometric model; The step of constructing a battery thermal model according to the physical parameters includes: The battery thermal model is constructed according to the thermodynamic parameters corresponding to each position in the three-dimensional geometric model.

3. The method according to claim 1 or 2, characterized in that: The method further comprises: Get the target detection area; In the target detection area, collecting the current density distribution in the target electrochemical thermal coupling model; When the current density distribution corresponding to the target detection area is greater than the current threshold corresponding to the target detection area, the target battery is determined to be in a dangerous state.

4. The method according to claim 3, characterized in that The target detection area is an overhang area in the target battery.

5. A current density simulation device, characterized in that: The device comprises: A parameter acquisition module is used to obtain the electrochemical parameters and physical parameters of the target battery; A model building module, used to build an electrochemical thermal coupling model according to the electrochemical parameters and physical parameters; the electrochemical thermal coupling model is used to indicate the temperature and current state of the target battery under the working environment; The model building module is further used to perform discharge simulation processing on the electrochemical thermal coupling model to obtain predicted discharge data of the electrochemical thermal coupling model under different discharge states; The model building module is further used to update the parameters of the electrochemical thermal coupling model based on the predicted discharge data under different discharge states and the actual discharge data of the target battery under different discharge states to obtain an updated electrochemical thermal coupling model; The model building module is further used to perform discharge simulation processing on the updated electrochemical thermal coupling model to obtain updated discharge data of the updated electrochemical thermal coupling model under different discharge states; The model building module is further configured to, when a difference between the predicted discharge data and the actual discharge data is less than a specified threshold, determine the updated electrochemical thermal coupling model as a target electrochemical thermal coupling model; A current density detection module, inputting a target charging current into the target electrochemical thermal coupling model, and detecting the current density distribution at each position in the target battery; The model building module is also used to: According to the electrochemical parameters, an electrochemical model is constructed; the electrochemical model is used to indicate the current distribution of each area of ​​the target battery under the target current state according to the target battery parameters; Constructing a battery thermal model according to the physical parameters; the battery thermal model is used to indicate the temperature change of each area of ​​the target battery; Based on the changing relationship between the target battery parameter and the temperature, and the corresponding relationship between the battery heat generation and the current state, the electrochemical model and the battery thermal model are coupled to form the electrochemical thermal coupling model.

6. A computer device, characterized in that: The computer device includes a processor and a memory, wherein the memory stores at least one instruction, and the at least one instruction is loaded and executed by the processor to implement the current density simulation method according to any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that: The storage medium stores at least one instruction, and the at least one instruction is loaded and executed by the processor to implement the current density simulation method according to any one of claims 1 to 4.

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